Eutrophication has become a major water environmental problem all over the world, and cyanobacterial blooms are one of the most common phenomena in eutrophic lakes. Thereafter, a large amount of cyanobacterial detritus will be produced after the blooms, and the effects of these detritus on water quality and biological communities are poorly studied. A 28-day mesocosm experiment was conducted in Meiliang Bay of Lake Taihu to study the effects of cyanobacterial detritus on nutrients dynamics and the biomass of aquatic organisms. We found that the concentration of nutrients increased rapidly after addition of Microcystis detritus, with the maximum mean concentration of total nitrogen (TN) and total phosphorus (TP) up to 3.86 mg/L and 0.36 mg/L, respectively. Meanwhile, phytoplankton biomass (Chl.a) increased dramatically, after detritus addition, in the first nine days, then it gradually declined to the end of the experiment. In addition, the biomass of periphyton decreased gradually after cyanobacterial detritus addition which may be mainly due to the decreasing water transparency caused by the rapid increase of Chl.a limiting the growth of periphyton. Meanwhile, the biomass of Limnodrilus spp. increased gradually, and peaked on day 20, indicating that cyanobacterial detritus facilitates the population development of Limnodrilus spp. Our results have implications for eutrophic lake management and better understanding the effects of cyanobacterial blooms on aquatic ecosystems.